Bluefin tuna 'critically endangered'

Of all the heavily fished tunas that face threats, southern bluefin stands out as a clear-cut case for "critically endangered" status, a scientific review by the International Union for the Conservation of Nature (IUCN) has found.

The finding is a blow to Australian fishers convinced that local bluefin stocks are improving, but underscores a recent federal government decision to demand that its continued fishing be made legally sustainable. Bluefin tuna is ought after in Japan for sashimi. The fishery's value is estimated at $1 billion by the international Commission for the Conservation of Southern Bluefin Tuna.

Overfishing including a hidden 20-year, $8 billion Japanese overcatch exposed by Australia has devastated the species over the past 50 years.

Its breeding population stands at less than 8 per cent of its original size, according to the federal Environment Department.

The conservation union reviewed southern bluefin's status in a broad examination of 61 important oceanic food species in the scombrid and billfish families. It concluded that the southern bluefin stood out among eight tuna species at greater risk than the Pacific bluefin and the Atlantic Ocean's northern bluefin.

"I'm afraid the statistics on the southern bluefin are very clear," Kent Carpenter, the global marine species assessment co-ordinator for IUCN, told The Age.

"All three bluefin tuna species are susceptible to collapse under continued excessive fishing pressure," Professor Carpenter said. "The southern bluefin has already essentially crashed, with little hope of recovery."

The study published in the journal Science found that the most efficient way to avoid further damage was to shut down the southern and Atlantic bluefin fisheries until stocks were rebuilt to healthy levels.

But it said this would cause increased economic hardship and give an incentive for illegal fishing. Instead there was an urgent need for effective management.

The Commission for the Conservation of Southern Bluefin Tuna has called a special meeting in Sydney next month to try to thrash out a new quota system that will quickly respond to evidence on the fish's population health. Meanwhile, an international catch limit of 9354 tonnes is in place for bluefin this year.

The Australian Tuna Association said recently that new scientific assessments would vindicate its belief that stocks are recovering.

The association's chief executive, Brian Jeffriess, said a 25 per cent quota cut in 2009 was premature and illogical, as was listing the species under the Environment Protection and Biodiversity Conservation Act.

But the Australian Marine Conservation Society continues to strongly oppose continued fishing.

Dangers to tuna stocks in the Australian region do not stop at bluefin. The Science article said that most long-lived and economically valuable fish species surveyed were threatened. These included bigeye (vulnerable), yellowfin and albacore (each near threatened), which can be found in Australian markets.

SOUTHERN BLUEFIN TUNA

Grows to over 200 kilograms and two metres in length.

Super-streamlined to snatch prey at 70 kilometres an hour.

First listed as critically endangered in 1996.

Mainly caught by Australian fishers using purse-seine nets.

International catch limit is 9354 tonnes.